1. Field of the Invention
This invention relates to defoaming compositions. More particularly, it relates to liquid compositions for the control of foam in aqueous systems.
2. Description of Prior Art
Foaming occurs in and frequently presents problems in numerous industrial processes in which aqueous solutions or suspensions are utilized. Due to the nature of the aqueous solutions or suspensions being processed, foaming may occur to such an extent as to interfere with the process being carried out. When foaming occurs to such an extent that process operations are impaired or product quality is degraded, chemical defoaming compositions are utilized to eliminate or retard interference by the foam of efficient operations.
In the paper industry foaming problems are experienced with black liquor, which is the spent cooking liquor derived from cooking wood pulp in accordance with the sulfate or kraft processes. Foaming also occurs in processing various pulp slurries in papermaking machines, waste disposal systems and the like.
A variety of chemical compositions have been used as defoamers and/or antifoamers. Depending on the nature of the system, any particular composition can be effective as either a defoamer, i.e., reduce or kill an existing foam, or as an antifoaming agent, i.e., will prevent foam from becoming established. Desirably the composition should perform both functions, however, this objective is not always attainable. Additionally, the stability and dispersibility of the composition to be used with foaming systems are important characteristics to be considered for a given application.
The compositions of this invention find applicability in various types of aqueous systems in which foams create problems, such as various papermaking processes, effluent disposal systems, sewage disposal systems, detergent-containing systems and other industrial systems in which the formation of foam creates a problem.
It is, therefore, the general object of this invention to provide versatile compositions for controlling, eliminating, or preventing foam in aqueous systems and which are stable, readily dispersible and have good antifatigue characteristics. The term "antifatigue" signifies a composition which has good staying power or effectiveness when used over a prolonged period of time.
Other objects, features and advantages of this invention will be evident from the following detailed description of the invention.